Number-indicating system



April 1-6, 1929. H. w. M DOUGALL 1,709,034

I NUMBER INDICATING SYSTEM Filed May 24, 1924 4 Sheets-Sheet 1 Z-HI /n van for Horn W Macfiauqa/l A ril16, 1929. H w, MacDoUGAL'L v 7 1,709,084

NUMBER INDI CATING SYSTEM Filed May 24, 1924 4 Sheets-Sheet 2 In van for h'am' W. NacDouga/l bz/ Af/Z/ April 16, 1929. w, MaCDOUGALL 1,709,084

NUMBER INDICATING SYSTEM Filed May 24, 1924 4 Sheets-Sheet 5 /n yen for Harri W MacDouqa/l by Affzj.

April 16, 1929. w, MacDOUGALL 1,709,084

'NUMBER INDICATING SYSTEM Filed May 24, 1924 4 She'eos$heet 4 //7 ven for Harry W" MacDouqa/l by A111 Patented Apr. 16, 1929.

UNITED STATES PATENT OFFICE.

HARRY W. MACDOUGALL, OF EAST ORANGE, NEW JERSEY, ASSIG-IIOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, New YORK.

OF NEW YORK, N. Y., A CORPORATION OF NUMBERJNDICATING SYSTEM.

Application filed May 24,

This invention relates to number indicating systems, and more particularly to number indicating systems adapted for use in telephone exchanges, and is especially adapted for use in conjunction with automatic telephone exchange systems.

The object ofthis invention is the provisior. in telephone systems where operators are employed for manually extending connections over trunks leading to succeeding switching devices, of means for indicating to the operator the identity of an automatically selected trunk to be used by her in extending such connections.

in accordance with this invention where a trunk has been automatically selected, Various circuits including resistance networks are established in succession overa single pair of wires to a group'of register relays whichmay or may not be operated in various combinations depending upon the resistance network used causing various circuits to be closed to light certain lamps which when lighted indicate to the'operator the particular trunk circuit selected.

Referring to the drawing, which constitutes-a part of the disclosure, Figs. 1 to 4 inelusive.v when arranged in the order shown in Fig. 5, illustrate so much of a telephone system embodying this invention as is neces' sary to a comprehensive understanding thereoi. Fig. 1 shows an operators position in a manual office provided with cord circuits for extendingsubscribers lines over interofiice trunk lines outgoing to distant mechanical oifices. Figs. 2 and 3 show two of a series of trunk selecting switches for automatically selecting an idle trunk outgoing from the operators position to the desired mechanical ollice. Fig. 4 illustrates the controlling and indicating equipment at the operators posi-. tion.

In the system disclosed connections are established by the operators in a manual originating oliice to any of a plurality of distant mechanical ofiices. For each mechanical 0:t-' lice to which the operators in the manual office have access, there is provided a group of interconnecting trunk lines terminating in switching apparatus in the mechanical ofiice. These groups of trunks are multipled so as to appear in outgoing trunk jacks at 1924. Serial No. 715,511.

each of the manual operators positions. The operator responds in the usual manner to a call initiated on any subscribers line which terminates at her position. Ascertaining the name of the called office and the number of the wanted line in that oflice, she manipulates the necessary apparatus at her position which causes the automatic selection of an idle trunk outgoing to t-lIGCZLllGCl ofiice, and the visual indication of the designation of the selected trunk. She then completes the connection by inserting the plug of the calling cord in the jack of the selected outgoing trunk and by means of a dial or register sender proceeds to set the switches atthe distant me chanical oflice to select the wanted line.

A plurality of selecting units are assigned to each group of interoflice trunks leading to the distant mechanical oflices, one of which otliccs is represented at DMO in Fig. 1. One of these selecting units consists of a plurality of step-by-step trunk selecting switches, such as 250 (Fig. 2) or 850 and a steer ing switch, such as 251 (Fig. 2). When the traffic between the manual office and the me chanical oifice is comparatively heavy a large group of interoflice trunk circuits is necessary. Inasmuch as the small step-by-step trunk selecting switches 250 and 350 only have a capacity of 20' trunks, it is necessary to provide a plurality of these switches for the entire group of outgoing trunks. Assuming that the outgoing trunk group contains 160 trunks, :8 trunk selecting switches are provided, each having access to a group of 20 trunks, with means for successively operating the switches to select an idle trunk.

At each operators position. a plurality of oflice keys, suchas 17, are provided. one for each distant mechanical office to which the operator has access. The depression of the ofiice key 17 individual to any mechanical ofiice initiates the selection of an idle trunk leading to such mechanical office. Any one of the 8 trunk selecting switches, such as 250 850. may be the first to be set in operation dependent upon the group of 20 trunks in which an idle trunk is taken for use in the last preceding connection. This switch hunts automatically and if an idle trunk is not found in this group of 20, returns to its normal position and initiates the hunting operation of the next succeeding selector also provided with a number of indicating lan'ips 4) for displaying before the operator the hundreds, tens and units designations of the automatically selected outgoing trunk. Since the trunk group said to contain 160 trunks, only two hundreds lamps, the No. (457) and the No. 1 (456)"lamps are required. A group oi? sensitive and marginal relays are provided which are so controlled by a resistance network as to operate in various combinations to light the proper indicating lamps designating the-number ot' the trunk seized by the trunk finder switch.

Having given a general outline of the tem, t he'detailed description of the operations involved in establishing a connection will now be described.

Let usassume that the subscriber at the substation *1 (Fig. 1), whose line terminates in the jack 2 at manual ofiice, wishes to converse with. the subscriber at substation 16,

whose line terminates in the distant mechanical oifice DMO. When the receiver is removed. at the substation 1, the line relay 4 is operated in series with the loop of the calling line, lighting the line lamp 5. The operator inserts the plug 3 in the jack 2, operating relays 6 and 8 and releasing the line relay 4,

thus extinguishing the line lamp 5. The listening key 27 is operated, connecting the call ing subscriber and the operator together and the name of the desired office and the number otthe desired line are given to the operator by the calling subscriber. The operator restores the listeningkey 27 to normal and depresses the ofi'ice key 17, which corresponds to the name 01 the distant mechanical. ofiice DMO.

hen the key 17 is depressed, relay 18 operates over an obvious circuit and locks by way of 19, 24, and 419 to ground Relay 13 operated, closes a' circuit to light lamp 404 as follows; battery, 26, 25, lamp 404, 419 to ground. The lamp 404 is lighted at this time to indicate tothe operator that a trunk to the distant mechanical olfice DMO (Fig; lilies not yet been picked.

Relay 18operated, also closes a circuit-to operate relay 300 as followsi battery, winding of relay 300, 23, 20 to ground. Relay 300 opera-ted, closes a circuit to operate the stepping magnet 303 ast'ollows battery, winding of stepping magnet 303, 304, 305, 211, 208, 309,

318, 212, 209, 321, 328 to ground. Stepping magnet 3030perated, opens at 304 its own operating circuit and releases, advancing the brushes 320 to 323 inch'isive, one step in a counter clockwise direction to the first terminal in each of the arcs 310 to 313, inclusive. The tri'inkfinder switch 350 is capable of hunting over a group of 20 trunks and the hunting' leadof every busy trunk will be connected to ground, causing the trunk to testbusy at the are 311. Let us assume that every trunk to which the trunk finder switch 350 has access is busy, in which case the first 20 terminals of the are 311 will be connected to ground, as indicated in the drawing. With the brushes 320 to 323, inclusive, resting upon the first terminal of their respective arcs, the circuit previously traced will be closed to reoperate the stepping magnet 303 toground by way of terminal 358 of are 311'. The stepping magnet opens at 304 its own operating circuit in themanner previously described and advances its brushes one step in a counter clockwise direction to the next terminal in each of the arcs 310 to 313, inclusive. As we have assumed that all the trunks are busy, this cycle of operations will continue until the brushes 320 to 323 are resting ,on the twentyfir'st terminal of their respective arcs,in which position a circuit will be closed to maintain the stepping magnet 303 operated, as follows: battery, winding of the stepping magnet 303, 319, 210, 219,317, 322, 316, 315, 314, 331 to ground. The stepping magnet 303 will remain operated until the steering si itch 251 advances, as hereinafter described. With the stepping magnet 303 operated, a circuit is now closed to operate the stepping magnet 206 of the steering switch 251 as follows: battery, winding ofthe steppingmagnet 206, 207, 213, 218, 324, 325, 326, 323, 306,375, 327', 307 to ground. Stepping magnet 206 operated, opens at 207 its own operating circuit and releases, advancing its brushes 210 to 215, inclusive, one step in a counter-clockwise direction, thus opening at the terminal 220 the holding circuit for thestepping magnet 303, which now releases, thus advancing the brushes 320 to 323, inclusive, anotherstep, in which positionbrushes 320, 322 and 313 are opened, brush 321 only remaining in contact with the terminal 328 of the are 311.

The advance of the brushes 210 to 215 of the steering switch 251 causes the trunk finder switch 250' to operateand search for an idle trunk in the trunk group to whi :h it has access. The stepping magnet 252 of the trunk finder switch 250 is now operated as follows: battery, winding of the stepping magnet 252, 253, 254, 211, 208, 309, 313, 212, 216, 271,- 217 to ground. Stepping magnet 252 operated opens at 253 its own operating circuit and releases, advancing its brushes 270 to 273, inclusive, one step a coun erclockwise direction to the first terminal'ot tl'ieir respective arcs 260 to 263, inclusive.

Let us assume that the first ten trunks in CIl tery, left windings of relays 454 and 452 this trunk group arealso busy, in which case ground will be connected to each of the first ten terminals of the are 261 and the stepping magnet 252 will continue to operate and release, advancing the brushes 270 to 273, inelusive, step by step until the terminals associated with the eleventh trunk are reached. Let us assume that the eleventh trunk is idle, in which case the terminal 228 will be free from ground, and accordingly, the stepping magnet 252 will not reoperate. A circuit will now be closed to operate relay 339 as follows: battery, winding of the stepping magnet 252, 253, 254, 211, 208, 309, winding of relay 339, 338 to ground. t should be observed that relay 339 was short circuited while the trunk finder switches were hunting for an idle trunk due to the presence of ground either on the hunting lead 209 or on the hunting lead 216, depending upon which trunk finder switch was in use. However, as soon as an idle trunk is found, the absence of ground on the hunting terminal removes the short circuit from the winding of relay 339, permitting it to operate. Relay 339 operated, connects solid ground at 337 by way of lead318, brush 212, lead 216 and brush 271, to the terminal 228, thence to the associated hunting terminals of the same trunk at all other trunk finder switches, causing this trunk to test busy to all other trunk finders.

Relay 339 operated, closes an obvious cirwit to operate relay 330,'thus extending lead 346 by way of 344, 342 anc 234 to the brush 214 of the steering switch, and the lead by way of 341, and 233 to the brush 215 of the steering switch.

Having found an idle trunk, we now proceed to indicate the number of the trunk seized to the operator at the manual switchboard (Fig. 1) The trunks available to the trunk tinder switch 250' are numbered from 20 to 39, and as the brushes 270 to 273, inclusive, are resting upon the eleventh terminal in each of the'arcs 260 to 263, inclusive, we have picked trunk No. 30; It is accordingly necessary to indicate this to the operator by lighting the corresponding lamps, 030 (Fig. 4). The following circuitis now closed to operate relays 340, 451 and battery, 26, 25, left windings of relays 453 and 451, 448, 346,344, 342, 234, brush 214, 217 low resistance winding L of relay-340 to ground. Re-

lays 451 and 453 operated, lock by way of their right windings and lead 359 to ground 348. Relay 340 operated, operates rela over an obvious circuit. Relay 354 operated,

. locks by way of 360 and 361 to ground under the control of relay 330. A circuit is also closed to operate relay 452 as iollows: bat- 7 447, 345, 34.3, 341, 233, 215, 227, 226, high resistance winding H of relay 340 to ground. Relay 452 operated, looks through its right of relay 330, 336.

winding by way of 359 to ground at 348, but relay 454, which is marginal, does not operate due to the high resistance winding H of relay 340 in series with it.

Relay 451 operated, closes an obvious circuit to operate relay 449, thus transferring the leads 345 and the windings of relays and 445 and relay 446, hereinafter more fully described. Relay 449 operated removes ground from the no trunk lamp 404 extinguishing it, as an indication to the operator that an idle trunk has been found. The operation of relay 449 also opens the locking circuit for relay 18 (Fig. 1) which releases. Relay 449 is designed to be slow to operate so that it will not operate immediately relay 451 operates, but will delay its operation long enough for relay 340 to operate, permitting relay 354 to operate and look under control of relay 330. lVith the leads 345 and 346 connected to the windings ofrelays 441 and 445, and relay 446, respectively, the leads 345 and 346 are con nected to ground instead of battery, permitting relay 340 to release. It should be ob served that relays 441, 445 and 446 will not operate under this circuit condition, prevent ing the possibility of false registration due to premature operation. Relay 340 released, closes a circuit to operate relay 355 as follows: battery, winding of relay 355, 362, 363 to ground. Relay 355 operated, transfers the leads 345 and 346-from the brushes 215 and 214 of the steering switch 251, to the brushes 273 and 272 respectively, of the trunk finder switch 250. It will be observed that the brush 272 is resting upon the open terminal 221. Hence, a circuitby way of lead 346 will not be closed and relays 441 and 445 will not operate. A circuit will be closed to 0p crate relays 446 and 352'as follows: battery, armature 364 of relay 330 (Fit 3), 33 365, 308, 366, 367, 373, 368, low res 'tance winding L of relay 352, 369, 222, terminal 223, brush 273, 224, e27, 370, 341,343, 345, 4.05, 406, left winding of relay 446 to ground. Belay 446 operated, locks by way of its right winding and lead 359 to ground at 348. Belay 446, operated, closes an obvious circuit to operate relay 444, which in turn operates relay 443, which in turn operates relay 442. Relays 442, 443 and 444 are designed to be slow to operate to insure the operation of relays 352 and 353 before leads 345 and 346 are transferred to the windings of relays 400 and 401, and relays 402 and 403, respectively. Relay 352 operated, closes a circuit to operate relay 353 as followst battery, armature 308, see. 307, 373, 368, 371, winding of relay 353, 372, 361 to ground. Relay 353 operated, opens at 373 the operating circuit for relay 352, which releases. Rela y 353 now locks over the following circuit battery, armature 364 of relay 330, 336, 365, 308, 366, 367, 374, winding of relay 353, 372, 361 to ground. A circuit is nou closed to operate relays 400 and 401 as follows: battery, through the windings oi relays 400 and 401 in parallel, 407, 408,405, 3.45, are, 341,370, 327, 375, 376, 377, 37s to ground.

A circuit is now closed to light the O hundreds lamp (457) as follows: battery, armature 410 oirelay 454, lamp 457, 411., 412 to ground. '11 circuit is also closed to light the tens lamp 3 (430) as follows: battery, armature 413 of relay 401, lamp 430, 414, 415, 416, 409, 411, 412 to ground. A circuit is also closed to light the 0 units lamp (440) as follows; battery, armature 417 of relay 403, lamp 440, 418,. 420, 421, 422, 412 to ground,

Accordingly, the 0 hundreds lamp (457), the 3 tons lamp 430) and the 0 units lamp (440) are lighted at the operators position, indicating to theoperator that trunk No. 30 in the first hundred has been seized. The operator now inserts the plug of the calling cord 10 1) in the jack 11, which is associated with the trunk circuit No. 30 which was seized by the trunk tinder 250 operating relay 13 and lighting supervisory lamp 12. Relay 13 operated, connects ground hy way of lead. 21, to the terminal 228 the trunk finder 250, thus providing substitute'ground to cause the trunk to testbusy after relay 339 releases in the manner hereinafter described. The operation of relay 13 closes a circuit to operate relay 333 as follows: battery, resistance 335, 334, winding of relay 333, 332, bruslr 270, terminal 260, '22 to ground. Relay 333 operated, opens at 302 the locking circuit for relay 300, which releases, and at 348, the locking circuits for the various relays 451, 452, 445, 446, 453, 454 and 441, releasing those relays which may happen I to be operated. Relay 300 released, opens the circuit through the winding of relay 339, whiclralso releases. .ltelay 339 relea ed, opens the circuit through relay 330, which releases, in turn releasing relay 354, which in turn releases relay 355. Relay 339 released,

'also' opens the operating circuit for relay 333, which releases. Therelease of relay .7

and opens the'trunk indicating leads and 344 and removes battery at its arn'iature 364 and. ground on its contact 361 from the winding of relay 353, which releases. The role of relay 451 releases relay 449 and the re lease of relay 446 allows relays 444, 443 and 4.42 to release in sequence. 1

The dialing key 28 is now operated, and the dial. 29 is operated and released in accordance with the digits conun'isinc the cor the called line 15, in the distant mechanic oilice DMO, setting); the switches 14 and 15 to extend the connection to theterininals of the called line. The called line 16 is signalled in a manner not shown, and upon responding, relay 9 is operated, eXtinguishing the calling e of supervisory lamp 12, and conversationtakes place between the calling subscriber 1 and the called subscriber 16. 1

When the receiver is replaced upon the switchhook atthe calling station 1, relay 8 releases and the supervisory lamp 7 is lighted. d hen the receiver, is replaced upon the s "itchhook at the called station 16, relay 9 releases, and the supervisory lamp 12 is lighted. {Vhen the plugs?) and lO are re moved from the jacks 2 and 11, relays (5 and 13 release and the circuit is restored to normal.

During the transfer of the leads 345 and 346 from one group of register relays to the next group by the operation of relay 449 or 411, it is important that the succeeding group of register relays should not be prematurely operated by way of the resistance networks formerly used to operate the previous group of register relays. To prevent such premature and false operation, each succeeding group of register relays is connected to the opposite side of the battery supply than that to which the preceding group was connected and each. succeeding resistance network is likewise arranged in this manner. The re sult is that wh n, for example, therelay 449 operates, the register relays 441, 445 and 446,

encounter either grounded or open-circuit conditions on leads 345 and 346 by way of brushes 214 and 215, and therefore will not operate. The operation otrelay 355 extends leads and 346 by way of brusl es 27 3 and 2'12 to either an open-circuit condition, a batvy circuit condition through the resistance ntworlt, or both, and circuits to operate reys 441, 445 and 446 or some particu unhination of these threerelays are closed. 11 like manner relays 400, 491, 402 and 403 re prevented from op mating until either clay 349 or relay 352 has operated, and, in urn operated either relay 351 or relay 353.

' What is claimed is:

1. Ina telephoneoxchange system, anoperators position, a pluralit of trunks said position,a trunk finder, means for operating said trunk finder to seizethe first idle trunk, and indicator devices including a plurality of marginal relays controlled progressively over a single pair of leads, said relays heing variably responsive to the setting of the trnnl-z finder toindicate the particular trunk seized.

in a telephone exchange system, an operators position, a plurality oi trunks arranged in groups at said position, trunk finders, one for each group, atrunh finder selecting; device, 'ineans controlled by said device for operating said trunk finders, whereby one of them seizes an idletrunl: in one of said groups, and indicator devices controlled ever a single pair ofleads, said indicator devices being variably responsive to the settings of the selecting device and of the trunk finder used to designate the specific trunk seized;

us-a 3. In a telephone exchange system, an operators position, a plurality of trunks arranged in groups at said position, trunk find erators position, a plurality of trunks ar-' ranged in groups at said position, trunk finders, one for each group, a trunk finder select-- ing device, means controlled by said device for operating said trunk finders, whereby one of them seizes an idle trunk in one of said groups, and indicator devices including a plurality of marginal'relays controlled progressively over a singlepair'ofleads, said relays being variably responsive to the settings of the selecting device and of the trunk finder used to designate the specific trunk seized.

5. In a telephoneeizchange system, an op erators position, aplurality of trunks arran ed in 'rouns at said position trunk findi a; c i 7 ers, one for each group, a steering switch, means for associatin the steering switch with any trunk finder, means controlled by the steering switch for operating the trunk finder thus associated, whereby it seizes an idle trunk, and indicator devices variably responsive to the settings of the steering and trunk finder switches to designate the specific trunk seized.

6. In a telephone exchange system, an operators position, a plurality of trunks arranged in groups at said position, trunk finders, one for each group, a steering switch, means for associating the steering switch with any trunk finder, means controlled by the .stcerings-witch for operating the trunk finde er thus associated, whereby it seizes an idle trunk andindicator devices controlled over asingle pair of leads, said indicator devices being variably responsive to the settings of r the steering and trunk finder switches to dos ignate the specific trunk seized.

- 7. In a telephone exchange system, an operators position, a plurality of trunks arranged in groups at said position, trunk finders, one for each group, a steering switch, means for associating the steering sw1tch with any trunk finder, meanscontrolled by the steering switch for operating the trunk finder thus associated, whereby its seizes an idle trunk, and indicator devices including a plurality of marginal relays variably responsive to the settings of the steering and trunk finder switches to designate the specific trunk seized. V a p 8. In a telephone exchange system, an operators position, a plurality of trunks arranged in groups at said position, trunk finders, one for each group, a steering switch, means for associating the steering switch with any trunk finder, means controlled by the steering switch for operating the trunk finder thus associated, whereby it seizes an idle trunk, and indicator devices including a plurality of marginal relays controlled progressively over a single pair of leads, said relays beingvariably responsive to the settings of thesteering and trunk finder switches to designate the specific trunk seized.

9. An indicating device comprising a plurality of control combinations, each consisting of a plurality of resistance networks, a

plurality of registers, a pair of leads for as-' sociatmg the registers with a particular con-' trol combination, and means for progressive ly transferring the leads from one resistance network of the control combination to an other and from one register to another.

10. An indicating device comprising a plurality of'control combinations, each consist ing of a plurality of resistance networks, aplurality of registers, a pair of leads'for associating the registers with a particular control combination, means for progressively transferring the leads from one resistance network of the control combination to another, and means for progressively transferring the leads from one register toanother.

11. An indicating device comprisin a plurality of control combinations, each consisting of a plurality of resistance networks, a plurality of registers, means for selecting any control combination, a pair of leads for associating the registers with the control combination selected, and means for progressively transferring the leads from one resistance network of the control combination to another and from one register to another.

12. -An indicating device comprising a plurality of control combinations, each consisting of a plurality of resistance networks, a plurality of registers, means for selecting any control combination, a pair of leads for associating the registers with the control combination selected, means for progressively transferring the leads from one resistance network of the control combination to another, and means for progressively transferring the leads from one register to another.

13, An indicating device comprising a plurality of control combinations, each consisting of a plurality of resistance networks, a plurality of registers, means for selecting any control combination, a pair of leads for associating the registers with the control combination selected, and switching means responsive to the operation of a particular register for transferring the'leads from such register and one of the resistance networks of thecontrol combination to the next succeeding register and another resistance net work. i

14. An indicating device comprising a plurality of control combinations, each consisting of a plurality of resistance networks, a

plurality of registers, means forselecting any control combination, a pair of leads for as sociating the registers with the control com bination selected, switching means responsive to the operation of a particular register for transferring he leads tothe next succeed 1ongregister, and switching means controlled.

7 5 operation of the first mentioned switching means for transferring the leads to another resistance network of the control combination, and means efi'cctive during the switching operations for delaying the operation of the succeeding register until both switching operations are completed.

16. An indicating device comprising a plurality oi? control combinations, each consisting of a plurality of resistance networks, a plurality of registers, means for selecting any control combination, a pair of leads for ssociating the registers with the control. combination selected, a relay responsive to the operation of a particular register for transferring the 40 leadsto the next succeeding register, and a relay controlled by the operation of the relay.

first mentioned for transferring the leads to another resistance network of the control combination. v 4.5 17. Anindicating device comprising a plurality of control combinations, each consisting of a plurality of resistance networks, a plurality of registers, means for sclecting any control combination, a pair of leads for asse-- 5o ciating the registers with the control combination selected, a relay responsive to the open,

7 control combination, whereby the registering devicesare progressively set; and a plurality ation of a particular register for transferring the leads to the next succeeding register, an-

ther relay controlled by the operation of the relay first mentioned for transferringthe leads to another resistance network of the control combination, and means efi'ective during the transfer operations for delaying the operation of the succeeding register until both 0 -transferoperations are completed.

18. In an indicating device, a plurality of controlcombinations comprising a plurality of resistance networks, means for selecting any control combination, aplurality otregis-- 5 itering devices, a pair of leads for associating icense the registering devices with the control combination selected, means for progressively transferring the leads from one resistance network to another and from one registering device to another whereby-the registering devices are progressively set, and a plurality of visible signals variably responsive to the settings oi said registering devices.

19. In an indicating device, a plurality oi control combinations comprising a plurality of resistance networks, means for selecting any control combination, a plurality of registering devices, a pair of leads for associating the registering devices with the control com bination selected; means for progressively transferring the leads from one resistance network to another, means for progressively transferring the leads from one registering device to anothehwhereby the registering devices are progressively set; and a plurality of visible signals variably responsive to the settingsof said registering devices.

20. In an indicating device, a plurality of control combinations comprising a. plurality of resistance networks, means for selecting any control combination, a'plurality of registering devices, a pair of leads for associating the registering devices with the control combination selected, and switching means responsive to the operation of a particular registering device for transferring the leads from such registeringdevice and one of theresistance networks to the next succeeding. registering device andanother resistance network whereby the registering devices are progressivelyset, and a plurality of visible signals variably responsive to the settings of said registering devices.

21. In an indicating device, a plurality of control combinations comprising a plurality of resistance networks, means for selecting any control combination, a plurality of registering devices, a pair of leads for associating the registering devices with the control COL-- bination selected; switching ineansrespon.

sive to the operation of a particular registermg device "for transferring the leadsto the next succeeding registering device, switching means controlled by the operation of thelir. mentioned switching means for transferring the leads to another resistance network-of the of visible signals variably responsive to the settings of said registering devices. 7 22. in an indicating device, a plura of control combinations comprising a pinrality of resistance networks. means tor selecting any control combination, plurality oirr isteringdevices, a pair o'fleatls for associating the registering devices with the;

control combination selectedp switching means responsive to the operation. of a narticnlar registering device for transtcrii o the leads to the next succceding registerany control combination, a plurality of regis- I tering devices, a pair of leads for associating device, switching means controlled the operation of the first mentioned switching means for transferring the leads to another resistance network, whereby the r 'ering devices are progressively set; means effective during the switching operations for delaying the setting of the succeeding registering device until both switching operations are completed, and a plurality of visible signals variably responsive to the settings of said registering devices.

23. In an indicating device, a plurality of control combinations comprising a plurality of resistance networks, means for selecting the registering devices with the control conibination selected; a relay responsi e to the operation of a particular registering device for transferring the leads to the next succeeding registering device, a relay controlled by the operation of the relay ii mentioned for transferring the leads to another resistance network, whll oy the registeri devices are progressively set; and a plural of visible signals variabl responsive in. settings of said rc 'sterin levices.

24. anindic ng device, a plurality of control combinations con'ipri ing a pluralit of networks, means for select any control combination, tefl a pair of -l dev' operation of a L istenng for transf I the leads to the next sue-- coed ing registe ing device, another relay controlled by the operation of the relay first n'ientioned for transferring the leadsto another resistance network, wherein; the registering devices are progressively sot; means o ed-tire during the transfer operati n r 5 la ing the operation of the succeeding llllt'll both transfer oper ons are if, and a plurality of visible signals 'ably responsive to the sett ngs ofsaid registering devices. a

25. In a telephone exchange system, plurality of lines, a selector for selecting said lines, means for identifying the lines in said selector comprising combinations of c at sources of different electrical characte.. tics individual to each of said lines, indicator for indicating a line according to the identifying means selected, and means for operating said selector to select and connect to said indicator a particular identifying means individual to the line selected.

26. In a telephone exchange system, a plurality of lines, line identifyingv means comprising combinations of current sources of different electrical characteristics individual a to each of said lines, an indicator, a selector identifying means to said indicator, means for operating said selector, and means operable in said indicator responsive to said connection for indicating the line selected.

27. In a telephone exchange system, aplurality of lines, line number identifying means comprising combinations of current sources of different electrical characteristics individual to each of said lines, an indicator, aselector for simultaneously selecting an idle line and an identifying means and connecting said identifying means to said indicator, means for operating said selector, and means operable in said indicator responsive to said connection for indicating the number of the lines selected.

28. In a telephone exchange system, a plurality of lines, a selector with stationary and movable contacts for selecting said lines, means for identifying the lines in said selector comprising current sources of different electrical characteristics connected to said stationary contacts selectable in combinations individual to each of said lines, an indicator for indicating a line according to the identifying means selected, and means for operating said movable contacts for selecting a line and an identifying means and connecting said identifying means to said indicator.

29. In a telephone exchange system, an operators position, a plurality of lines at said position, an indicator, a selector with station ary and movable contacts for selecting said lines, means for identifying the lines in said selector comprising current sources of different electrical characteristics connected to the stationary contacts selectable in variable combinations for operating said indicator, means for setting said movable contacts in motion for simultaneouslyfinding an idle line and an identifying means, and means in said indicator responsive to said identifying means for indicating the number of the idle line selected. V y

80. In a telephone exchange system,an operators posit-ion, a plurality of lines at said position, a selector with stationary and movable contacts for selecting said lines, means for identifying the lines in said selector comprising current sources of different electrical characteristics connected to said stationary contacts selectable in variable combinations for operating said indicator, means for setting said movable contacts in motion for simultaneously finding an idle line and an identifying means, means for interconn cting said indicator and said identifying means by a single pair of conductors, and means in said indicator responsive to said identifying means for indicating the number of the line selected.

81. In a telephone exchange system, an operators position, a plurality of lines at said position, an indicator including a plurality of marginal electromagnetic devices, a selector for selecting said lines, means for identifying lected, and means responsive to said connecthe lines in said selector comprising combination for operating certain of said marginal tions of current sources of difierent electrical electromagnetic devices according to the 10 characteristics individual to each of said identifying means selected.

'5 lines, means foroperating said selector to se- In Witness whereof, I hereunto subscribe lectand connect to said indicator a particular my name this 22 day of May A. 1)., 1924. identifying means individual to the line se- 1 HARRY XV. MAODOUGALL. 

